126 WAVES OF SAND AND SNOW 



of the barchan differed from that shown in the 

 preceding illustrations, the summit being near the 

 weather end ; but the position of the summit shifted 

 to leeward until there was a long, gentle weather 

 slope and a short lee cliff. By this time erosion- 

 grooves began to appear at the weather end, show- 

 ing that the patch of snow-sand, or rather so much 

 of it as was not required to fill up the depression 

 in the old, hard surface, was now travelling 

 forward (Figs. 7, 8, and 9). 



The best measurements which I obtained of 

 ripples in snow-sand were those of the group 

 shown in Plate XV., which were taken after 

 the wind had ceased. They are as follows: — 



The ripples of this group, which diminish slightly 

 in size from windward to leeward, covered a patch 

 of snow-sand which had filled a depression in the 

 surface of the old, hard snow. 



